Process for preparing hydroxymethylated phosphines

ABSTRACT

PRIMARY AND SECONDARY PHOSPHINES AS WELL AS PHOSPHINE ITSELF REACT WITH FORMALDEHYDE TO PRODUCE HYDROXYMETHYLATED TERTIARY PHOSPHINES AT A TEMPERATURE BETWEEN ABOUT 20-130* C. AT ABOUT ATMOSPHERIC TO SLIGHTLY ELEVATED PRESSURES. THE REACTION PROCEDES SMOOTHLY TO AFFORD A PRODUCT OF EXCELLENT PURITY IN NEARLY QUANTITATIVE YIELDS.

United States Patent Office 3,660,495 PROCESS FOR PREPARING HYDROXY-METHYLATED PHOSPHINES Kmgso Chingtsung Lin, Newark, Ohio, assignor toHooker Chemical Corporation, Niagara Falls, N.Y. N Drawing. Filed Dec.10, 1969, Ser. No. 883,990 Int. Cl. C07f 9/02 U.S. Cl. 260-6065 P 7Claims ABSTRACT OF THE DISCLOSURE Primary and secondary phosphines aswell as phosphine itself react with formaldehyde to producehydroxymethylated tertiary phosphines at a temperature between about20-130 C. at about atmospheric to slightly elevated pressures. Thereaction procedes smoothly to afford a product of excellent purity innearly quantitative yields.

BACKGROUND OF THE INVENTION BRIEF DESCRIPTION OF THE INVENTION It hasnow been discovered that the reaction of formaldehyde, in its monomeric,trimeric (trioxane) or polymeric (paraformaldehyde) form reacts readilywith 'PH RPH and R PH where R is alkyl of 1 to 18 carbon atoms,cycloalkyl of 5 to 18 carbon atoms, aryl of 6 to 18 carbon atoms, andtheir hydroxy, lower'alkoxy, lower alkylmercapto, lower alkylamino, andlower carboalkoxy derivatives thereof, in the absence of a catalyst andunder a pressure of from 1-10 atmospheres at a temperature from about 20to about 100 C. to produce the corresponding hydroxymethylated phosphinederivative (HOCHQ P, RP(CH 0H) and R PCH OH in near theoretical yields.The non-catalyzed production of hydroxymethylated phosphine derivativesis especially surprising in view of the fact that the prior artgenerally teaches the necessity of employing HCl or a metal saltcatalyst in the reaction of formaldehyde with phosphine or, wherecatalysts have been avoided, the product obtained has been thetetrakis-hydroxymethyl phosphonium Hydroxide salt.

The present discovery affords the art a simple, direct route tohydroxymethylated phosphines without the necessity of complicatedprocess steps for catalyst removal, product conversion to the desiredphosphine derivative, and relatively strenuous process conditions oftemperature and/or pressure while still producing nearly quantitativeyields of the desired product. One of the disadvantages attending theuse of metal salt catalysts such as H PtCl resides in the production ofa light yellow colored impure product.

DETAILED DESCRIPTION OF THE INVENTION In accordance with this inventionthere is provided a process for the production of a hydroxymethylatedphosphine which comprises reacting formaldehyde with a phosphine of theformula:

3,660,495 Patented May 2, 1972 wherein R is a member selected from thegroup consisting of alkyl of 1-18 carbon atoms, cycloalkyl of 5-18carbon atoms, aryl of 6 to 18 carbon atoms and their hydroxy, loweralkoxy, lower alkylmercapto, lower alkylamino, and lower carboalkoxyderivatives and n is an integer from 0-2, under a pressure of from about1-10 atmospheres at a temperature of from about 20-100 C. for a periodof time sufiicient to substantially complete the reaction and thereafterincreasing the temperature of the reaction mixture to from about -130 C.in vacuo to remove Water and residual unreacted formaldehyde.

In a preferred embodiment, the temperature of reaction is betweenabout-65-100 C. and the pressure is from 1 to 5 atmospheres.

When working with phosphine itself, no extraneous solvent is needed toassist in the reaction. The use of formaldehyde as a 37 percent aqueoussolution provides a solvent for the formaldehyde. However, whenperforming the reaction with substituted phosphines, it is desirable toemploy a solvent. The solvent must be inert toward the reactants andunder the conditions of the reaction. Illustrative examples of inertsolvents are pentane, hexane, heptane, octane, benzene, toluene,cyclohexane, tetrahydrofuran, and the like.

The rate of reaction of a phosphine with aqueous formaldehyde may beincreased by the addition of a small amount of a tetraalkylphosphoniumsalt such as tetrakishydroxymethyl "phosphonium chloride if desired.However, where a very pure product is desired, the introduction of acatalyst may be completely avoided in conformity with the instantinvention.

Examples of various phosphine reactants applicable to the process ofthis invention are: phosphine and the monoor disubstituted phosphinederivatives in which the substituent is alkyl (methyl, ethyl propyl,iso-propyl, butyl, octadecyl, and the like); hydroxyalkyl(Z-hydroxyethyl, 2-hydroxy propyl, and the like); aryl (phenyl, 4-hydroxyphenyl, naphthyl, 4-tolyl, 4-ethylphenyl, 2,4,5- trimethylphenyl,4 phenylmethylphenyl, 4 phenethylphenyl, 4 methoxyphenyl, 4ethylmercapto phenyl, 4 carbethoxyphenyl, 4 methylaminophenyl, 4diethylaminophenyl, and the like); and cycloalkyl (cyclopentyl,cyclohexyl, 2,4,6 tri methyl cyclohexyl, hexa hydro-naphthyl, and thelike).

Example I One hundred grams of 37 percent aqueous formaldehyde in a 250milliliter Parr shaker bottle was charged with PH from a 4 litercylinder at 50 pounds per square inch gauge and heated to 65-70 C. withvigorous shaking. The pressure dropped to 45 pounds per square inchguage in 20 minutes. The cylinder was repressurized with PH to 50 poundsper square inch gauge and the reaction repeated in two successive steps,to give a total of 15 pounds per square inch gauge drop in pressure overa total period of 1.5 hours of heating and shaking. A total of 6.1 gramsof PH, had been consumed. The resulting clear solution was transferredto a 250 milliliter flask and water and unreacted formaldehyde wasstripped 01f in a. rotary evaporator on a steam bath under 22.24millimeters mercury pressure for one hour and for an additional hour at2-3 millimeters mercury pressure.

The colorless viscous liquid residue was cooled to room temperature andcrystallized by seeding with pure trishydroxymethylphosphine crystals togive 27 grams (55.0% conversion based on formaldehyde and greater than100% conversion based on the -PH;, used) of product of melting point54-57 C.

The chemical shift of the phosphorus-31 nuclear magnetic resonancespectrum was 24.1 p.p.rn. (singlet) indicating that the compound washis-hydroxymethylphosphine.

Elemental analysis.-Calculated for C H PO (percent): P, 25.00. Found(percent): P, 24.70.

Example II The infra-red spectrum of the crude product was 3300(indicating the presence of an associated -OH bond), 2900, 2750, 1460,1380 (indicating CH, CH and CH bands) and 1015 reciprocal centimeters(CH 0 bond). The phosphorus -31 nuclear magnetic resonance spectrumindicated the presence of a pure tertiary phosphine with a chemicalshift of 27.6 ppm. ('with a reference of 85 percent H PO Elementalanalysis.Calculated for C H OP (percent): C, 74.94; H, 13.33; P, 7.74.Found (percent): C, 75.07; H, 13.37; P, 7.63.

By substituting various primary and secondary phosphines for thedidodecyl phosphine of Example IV, similar results are obtained. Thereaction in each case procedes smoothly to afford excellent yields ofhigh purity product.

TABLE I Conv. based 011 Anal., celud I- for p, 25.00; CHEO PH; PHa Temp.Time (HO CH;)aP CHzO PH: found Run (mole) (p.s.i.g.) (mole) 0.) Catalyst(g.) (hrs.) (mole) (percent) (percent) (percent) 1. 23 5033 0.2 25Barley Ni (1.0).--. 9 0.266 65 100 22. 00 1. 23 50-33 0. 2 25 N0 11 0.271 66 100 1. 23 50-25 0. 294 25 H2PlZCla-6H2O (0.4) 1. 5 0.32 78 10021. 00

HO OH 1. 23 5033 0. 2 25 Ni(C O)4 (0.4)..- 9 0. 27 05. 5 100 1. 23 50-360. 16 65 N0.. 1. 0 0. 22 53. 0 100 1. 23 50-45 0. 175 65-70 No 1. 5 0. 249. 0 100 24. 7 1. 85 50-45 0. 21 68 No 1. 5 0. 24 41. 0 100 24. 7 2. 46Atm. 0.69 25 HqPtClrGHzO (0.4)-. 3.0 0. 69 84. 0 100 20. 0 1. 85 Atm =0.25 65 No 3. 0 0. 175 42. 5 70 I Pressure reading 014 liter cylinder. bThe presence of hydroquiuone improved the color of the product.

Example III To demonstrate the eflect of acid catalysis and the use oftetrakis-hydroxymethyl phosphonium chloride in the reaction of phosphinewith formaldehyde, the following experiments were performed. It may benoted that excellent yields of THP (tris-hydroxymethyl phosphine) wereobtained in the absence of an acid catalyst (Run 3) and in the presenceof HCl or THPC (tetrakis-hydroxymethyl phosphonium chloride) with verysmall amounts of by-product formation. Each of the tabulated runs werecarried out in a Parr shaker bottle pressurized with phos- For example,two similar runs of the above reaction were carried out butmono-octyland dioctylphosphine were used.

Both runs gave similar results as the previous runs. The infra-redspectra of these two products were identical in the shape of theirabsorption bands with didodecyl hydroxymethylphosphine. These threealkylhydroxymethyl phine from a 4 liter cylinder. phosphine derivativeswere oxidized by hydrogen perox- 0 HX H20 PH; Temp Time THP Q (mole)(mole) (p.s.i.g.) C (min) percent 'II-IPX CH3 (CH0H)2 1. 0 1.0 -40 80-0030 50 (44% HX=HCOOH 0. 2a 1.2 0040 80-00 45 72.5 18 10 HX=HCOOH 0 1. 800-40 80-00 120 05 5 0. 10 2. 0 00-40 80-00 30 66. 0 17 17 HX=HC 0 OH 14 2. 0 60-40 80-00 30 04.4 HX=THP C 0. 024 2.0 60-40 80-90 30 04.3 X=HCl Grains.

Example IV ide in acetone to give the corresponding phosphine oxides.

A reaction mixture of 37.0 g. (0.1 mole) of didodecylphosphine and 60ml. (0.6 mole) of 37 percent aqueous formaldehyde in 300 milliliters oftetrahydrofuran was refluxed for 1.5 hours. After heating, the reactionmixture was heated on a steam bath under reduced pressure of a wateraspirator and latter by a vacuum pump to remove the solvent andunreacted formaldehyde. Heating on the steam bath was continued at apressure of from 0.25 to 1.0 millimeter mercury until a reaction productof constant weight was obtained. The crude product weight 41.0 grams(100 percent conversion based on didodecylphosphine sed).

From the study of infra-red spectra of these oxides, which aresummarized in the following table, it is evident that the structure ofthe hydroxymethylphosphine oxides exhibited intermolecular hydrogenbonding as shown in the following:

P=O absorption band, 1180-1260 cmr decreased to the range of 1135- cm.-

O---H Shifted from 3350-3300 cmr for hydroxymethyl O phosphlnes to 3200cm.-

R R2l.-CHz t--- Increased from 1005-1015 Gill-' to 1015-1055 crnrINFRA-RED ABSORPTION BAND IN CD15 O O (CmHzQzIiiCHzOH (CBH11)2)CH20HCsH17i P(CH OH) (HOCHQI E CHa 3,200 3,200 3,225 (a broad s band)-..3,250 (5 broad). 2,900." 1... 2,900 1 2,900 2,900.

What is claimed is:

1. A process for the production of a hydroxymethylated phosphine whichcomprises reacting, in the presence of a catalytic amount of atetraal'kyl phosphonium salt, formaldehyde with a phosphine of theformula wherein R is a member selected from the group consisting ofalkyl of 1-18 carbon atoms, cycloalkyl of 5-18 carbon atoms, aryl of6-18 carbon atoms and their hydroxy, lower al'koxy, lower alkylmercapto,lower alkylamino, and lower carboalkoxy derivatives and n is an integerfrom -2, under a pressure of from about 1-10 atmospheres at atemperature of from about 20-100 C. for a period of time sufficient tosubstantially complete the reaction and thereafter increasing thetemperature of the reaction mixture to from about 100-130 C. in vacuo toremove water and residual unreacted formaldehyde.

2. The process of claim 1 in which the temperature of reaction isbetween about 65-100 C.

3. The process of claim 1 in which the pressure is between aboutatmospheric to about atmospheres.

4. The process of claim 1 in which n is 0.

5. The process of claim 1 in which n is 2. 2

6. The process of claim 1 in which the reaction is conducted in thepresence of an inert solvent.

7. The process of claim 1 in which said tetraalkyl phosphonium salt istetrakis-hydroxymethyl phosphonium chloride.

References Cited UNITED STATES PATENTS OTHER REFERENCES Houben-Weyl,Methoden der Organischen Chemie (1963), vol. 12/1, p. 29.

TOBIAS E. LEVOW, Primary Examiner W. F. W. BELLAMY, Assistant Examiner

